[PATCH v4] elf: Also try DT_RUNPATH for LD_AUDIT dlopen [BZ #28455]

[H.J. Lu]

Changes in v4:

1. Move the RUNPATH search for LD_AUDIT dlopen after the other RUNPATH
search
2. Split one test per line and sort.

DT_RUNPATH is only used to find the immediate dependencies of the
executable or shared object containing the DT_RUNPATH entry.  Update
LD_AUDIT dlopen call to try the DT_RUNPATH entry of the executable.
This partially fixes BZ #28455.
---
 elf/Makefile       | 20 +++++++++++++++++---
 elf/dl-load.c      | 37 ++++++++++++++++++++++++++++++++-----
 elf/tst-audit14a.c |  1 +
 3 files changed, 50 insertions(+), 8 deletions(-)
 create mode 100644 elf/tst-audit14a.c

diff --git a/elf/Makefile b/elf/Makefile
index fe42caeb0e..625b1a023f 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -249,10 +249,19 @@ ifneq ($(selinux-enabled),1)
 tests-execstack-yes = tst-execstack tst-execstack-needed tst-execstack-prog
 endif
 ifeq ($(have-depaudit),yes)
-tests += tst-audit14 tst-audit15 tst-audit16
+tests += \
+  tst-audit14 \
+  tst-audit14a \
+  tst-audit15 \
+  tst-audit16 \
+
 ifeq ($(run-built-tests),yes)
-tests-special += $(objpfx)tst-audit14-cmp.out $(objpfx)tst-audit15-cmp.out \
-		 $(objpfx)tst-audit16-cmp.out
+tests-special += \
+  $(objpfx)tst-audit14-cmp.out \
+  $(objpfx)tst-audit14a-cmp.out \
+  $(objpfx)tst-audit15-cmp.out \
+  $(objpfx)tst-audit16-cmp.out \
+
 endif
 endif
 endif
@@ -1529,6 +1538,8 @@ tst-auditmany-ENV = \
 LDFLAGS-tst-audit14 = -Wl,--audit=tst-auditlogmod-1.so
 $(objpfx)tst-auditlogmod-1.so: $(libsupport)
 $(objpfx)tst-audit14.out: $(objpfx)tst-auditlogmod-1.so
+LDFLAGS-tst-audit14a = -Wl,--audit=tst-auditlogmod-1.so,--enable-new-dtags
+$(objpfx)tst-audit14a.out: $(objpfx)tst-auditlogmod-1.so
 LDFLAGS-tst-audit15 = \
   -Wl,--audit=tst-auditlogmod-1.so,--depaudit=tst-auditlogmod-2.so
 $(objpfx)tst-auditlogmod-2.so: $(libsupport)
@@ -1555,6 +1566,9 @@ tst-audit17-ENV = LD_AUDIT=$(objpfx)tst-auditmod17.so
 $(objpfx)tst-audit14-cmp.out: tst-audit14.exp $(objpfx)tst-audit14.out
 	cmp $^ > $@; \
 	$(evaluate-test)
+$(objpfx)tst-audit14a-cmp.out: tst-audit14.exp $(objpfx)tst-audit14a.out
+	cmp $^ > $@; \
+	$(evaluate-test)
 $(objpfx)tst-audit15-cmp.out: tst-audit15.exp $(objpfx)tst-audit15.out
 	cmp $^ > $@; \
 	$(evaluate-test)
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 721593135e..1c90801903 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -2143,14 +2143,16 @@ _dl_map_object (struct link_map *loader, const char *name,
 
       fd = -1;
 
+      struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
+      bool did_main_map;
+
       /* When the object has the RUNPATH information we don't use any
 	 RPATHs.  */
       if (loader == NULL || loader->l_info[DT_RUNPATH] == NULL)
 	{
 	  /* This is the executable's map (if there is one).  Make sure that
 	     we do not look at it twice.  */
-	  struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
-	  bool did_main_map = false;
+	  did_main_map = false;
 
 	  /* First try the DT_RPATH of the dependent object that caused NAME
 	     to be loaded.  Then that object's dependent, and on up.  */
@@ -2186,13 +2188,38 @@ _dl_map_object (struct link_map *loader, const char *name,
 			loader ?: GL(dl_ns)[LM_ID_BASE]._ns_loaded,
 			LA_SER_LIBPATH, &found_other_class);
 
+      /* Make sure that we do not look at RUNPATH in the executable
+	 twice.  */
+      did_main_map = false;
+
       /* Look at the RUNPATH information for this binary.  */
       if (fd == -1 && loader != NULL
 	  && cache_rpath (loader, &loader->l_runpath_dirs,
 			  DT_RUNPATH, "RUNPATH"))
-	fd = open_path (name, namelen, mode,
-			&loader->l_runpath_dirs, &realname, &fb, loader,
-			LA_SER_RUNPATH, &found_other_class);
+	{
+	  did_main_map = loader == main_map;
+	  fd = open_path (name, namelen, mode,
+			  &loader->l_runpath_dirs, &realname, &fb, loader,
+			  LA_SER_RUNPATH, &found_other_class);
+	}
+
+      /* When processing the lookup we may need to additionally try
+	 DT_RUNPATH in the executable for a glibc internal dlopen call
+	 when looking for audit modules.  */
+      if (__glibc_unlikely (mode & __RTLD_AUDIT)
+	  && fd == -1
+	  && !did_main_map
+	  && main_map != NULL
+	  && main_map->l_type != lt_loaded)
+	{
+	  struct r_search_path_struct l_rpath_dirs;
+	  l_rpath_dirs.dirs = NULL;
+	  if (cache_rpath (main_map, &l_rpath_dirs,
+			   DT_RUNPATH, "RUNPATH"))
+	    fd = open_path (name, namelen, mode, &l_rpath_dirs,
+			    &realname, &fb, loader ?: main_map,
+			    LA_SER_RUNPATH, &found_other_class);
+	}
 
       if (fd == -1)
         {
diff --git a/elf/tst-audit14a.c b/elf/tst-audit14a.c
new file mode 100644
index 0000000000..c6232eacf2
--- /dev/null
+++ b/elf/tst-audit14a.c
@@ -0,0 +1 @@
+#include "tst-audit14.c"
-- 
2.33.1